Merge template functions "dict/Dict/mergeinto" (#23932)

One of the steps in #23328


Before there were 3 different but similar functions: dict/Dict/mergeinto

The code was just copied & pasted, no test.

This PR defines a new stable `dict` function, it covers all the 3 old
functions behaviors, only +160 -171


Future developers do not need to think about or guess the different dict
functions, just use one: `dict`

Why use `dict` but not `Dict`? Because there are far more `dict` than
`Dict` in code already ......

modules/util/util.go

@@ -6,7 +6,6 @@ package util
 import (
 	"bytes"
 	"crypto/rand"
-	"errors"
 	"fmt"
 	"math/big"
 	"strconv"
@@ -117,29 +116,6 @@ func NormalizeEOL(input []byte) []byte {
 	return tmp[:pos]
 }
 
-// MergeInto merges pairs of values into a "dict"
-func MergeInto(dict map[string]interface{}, values ...interface{}) (map[string]interface{}, error) {
-	for i := 0; i < len(values); i++ {
-		switch key := values[i].(type) {
-		case string:
-			i++
-			if i == len(values) {
-				return nil, errors.New("specify the key for non array values")
-			}
-			dict[key] = values[i]
-		case map[string]interface{}:
-			m := values[i].(map[string]interface{})
-			for i, v := range m {
-				dict[i] = v
-			}
-		default:
-			return nil, errors.New("dict values must be maps")
-		}
-	}
-
-	return dict, nil
-}
-
 // CryptoRandomInt returns a crypto random integer between 0 and limit, inclusive
 func CryptoRandomInt(limit int64) (int64, error) {
 	rInt, err := rand.Int(rand.Reader, big.NewInt(limit))